The present invention relates generally to operations performed in conjunction with a subterranean well and, in an embodiment described herein, more particularly provides apparatus and methods for completing a wellbore junction.
Lateral wellbores are frequently drilled extending outwardly from parent wellbores. A problem associated with the junctions between these parent and lateral wellbores is how to provide access to each of the wellbores, while isolating flow passages therein and preventing migration of fluids between formations intersected by the junctions from other formations intersected by the wellbores. Many solutions have been proposed for solving this problem, however, most of these rely upon cement for isolating the flow passages and preventing migration of fluids, and/or require additional drilling or milling through the cement or tubular members positioned in the junction.
It would be advantageous to provide a lateral wellbore junction in which an apparatus may be assembled which provides access to the lateral and parent wellbores. The apparatus should include flow passages extending through housings adapted for connection to tubular members extending into the lateral wellbore, and the upper and lower parent wellbores. Fluid may then flow, and equipment may pass, from or into each of the wellbores through the flow passages in the apparatus and, thus, through the wellbore junction.
The apparatus should also include provisions for securing the housings to each other, so that the apparatus is not damaged or rendered ineffective by temperature and pressure variations, etc. The method of securing the housings to each other should be convenient and economical to perform. Additionally, the method should be performable within the well.
The apparatus should include provisions for scaling the housings, so that the flow passages therein are isolated from fluid communication with the wellbores in which the housings are positioned. Since the housings may be assembled to each other within the well, the method of sealing should accommodate and be compatible with the method of securing the housings to each other.
Furthermore, the apparatus should be adapted for use in an overall wellbore junction completion in which the formation intersected by the wellbore junction is isolated from other formations intersected by the wellbores. Thus, the housings of the apparatus should be configured for attachment to tubular members extending into, and sealingly engaged within, each of the wellbores.
It is an object of the present invention to provide such an apparatus and associated methods of completing a wellbore junction. Accordingly, a sealed lateral wellbore junction, including an apparatus which is assembled downhole, is described below in a particular embodiment of the invention. Additionally, apparatus and methods which facilitate the wellbore junction completion are also provided.